Post AYgTvJOscKF2YVQfIW by dalias@hachyderm.io
(DIR) More posts by dalias@hachyderm.io
(DIR) Post #AYa563TgUeuSYVwVuK by mjg59@nondeterministic.computer
2023-08-10T07:38:54Z
3 likes, 5 repeats
STOP DOING SPECULATIVE EXECUTIONINSTRUCTIONS WERE NOT MEANT TO HAVE REVERSIBLE SIDE EFFECTS
(DIR) Post #AYa5S9qPVH7Ofj70XA by matzipan@hachyderm.io
2023-08-10T07:43:12Z
0 likes, 0 repeats
@mjg59 a new cpu bug?
(DIR) Post #AYa5aobPqjCTOjE7DU by Rairii@haqueers.com
2023-08-10T07:43:17Z
0 likes, 0 repeats
@mjg59 wanted to reverse the effect of an instruction for a laugh? we had a tool for that it was called junk code obfuscation
(DIR) Post #AYa5wPjB0w1CcY9iiG by a000d4f7a91939d0e71df1646d7a48@anticapitalist.party
2023-08-10T07:46:37Z
0 likes, 0 repeats
@mjg59 sure speculative execution has its flaws, but you are just not seeing the bigger picture.In quantum computers, every instruction but collapsing the state is perfectly reversible, so speculating is perfectly fine, you can just go back to the previous step in a few operations. Intel and AMD are just getting ready for the next big thing(just in case, that's sarcasm)
(DIR) Post #AYa6FrcpW1Wee6SgFs by mjgardner@social.sdf.org
2023-08-10T07:47:03Z
0 likes, 0 repeats
@mjg59 @0xabad1dea THEY HAVE PLAYED US FOR ABSOLUTE FOOLSAND THEN REALIZED THEIR MISTAKE AND WE WERE NONE THE WISER
(DIR) Post #AYa6xTrXE5xRgk8baK by mjg59@nondeterministic.computer
2023-08-10T07:59:59Z
0 likes, 0 repeats
@apaleslimghost @a000d4f7a91939d0e71df1646d7a48 speculative execution may leak a lot of PII, but it also helps a lot of instructions get retired in time, so, it;s impossible to say if its bad or not,
(DIR) Post #AYa7SzCIm20XqhsGbA by noodle@aus.social
2023-08-10T08:04:01Z
0 likes, 0 repeats
@mjg59 "YES DOING THAT THING YOU DIDN'T NEED, BEFORE YOU DIDN'T ASK, IMPROVES PERFORMANCE" - Statements dreamt up by the utterly Deranged
(DIR) Post #AYa975y17jLoNksknQ by womump@mastodon.social
2023-08-10T08:23:10Z
0 likes, 0 repeats
@mjg59 says the guy on nondeterministic.computer ;)
(DIR) Post #AYaCPXseNeuo1rrSIi by ljrk@todon.eu
2023-08-10T09:01:10Z
0 likes, 0 repeats
@mjg59 Maybe we should follow-through with a "fully" functional CPU without side-effects, by now the perf difference can't be that big, and we could theoretically always do speculation there, safely :-p
(DIR) Post #AYahxORr3KplCUwoYi by dalias@hachyderm.io
2023-08-10T14:54:52Z
0 likes, 0 repeats
@mjg59 This, but unironically.
(DIR) Post #AYai6prcUY2YpoV9RA by matt@toot.cafe
2023-08-10T14:56:01Z
0 likes, 0 repeats
@mjg59 All right, is there a way that we software developers can disable all speculative execution on our own machines so we can find out the new performance targets that we'll eventually have to meet?
(DIR) Post #AYaiWm8YyD2So0nO5o by ncweaver@thecooltable.wtf
2023-08-10T15:01:10Z
0 likes, 0 repeats
@mjg59 @alanc Eh, sounds like a good idea{erk}Eh, nah, branch misprediction, we want to keep speculating...
(DIR) Post #AYakbobDRXPznXjEQq by acsawdey@fosstodon.org
2023-08-10T15:24:41Z
0 likes, 0 repeats
@mjg59 STOP LETTING PEOPLE YOU DON'T TRUST USE YOUR COMPUTER😁
(DIR) Post #AYamATrkcYa3aIYYk4 by muvlon@hachyderm.io
2023-08-10T15:42:15Z
0 likes, 0 repeats
@mjg59 YEARS OF UARCH OPTIMIZATIONS YET NO PERFORMANCE GAINS FOUND THAT WEREN'T EVENTUALLY UNDONE BY MITIGATIONS
(DIR) Post #AYamluOEy54YYtbGTo by lifts@bitbang.social
2023-08-10T15:48:51Z
0 likes, 0 repeats
@mjg59 But, my side-channel attacks. What will they eat for dinner if you put them out of a job?
(DIR) Post #AYaqE053hguKBKiNTU by khoji@ieji.de
2023-08-10T16:28:59Z
0 likes, 0 repeats
@a000d4f7a91939d0e71df1646d7a48 @mjg59 In related news, Airbus is working on a voice recognition system for airliners that will understand and respond to the radio instructions from the air traffic controllers.“Please use runway 14 west.”“Here is what I found on the Internet about Vivienne West’s runway show in 2014”
(DIR) Post #AYb2DtG4Gh0MTLZuKm by alcinnz@floss.social
2023-08-10T18:41:58Z
0 likes, 0 repeats
@mjg59 How about instructions with no side-effects?(Haskeller here)
(DIR) Post #AYb8ENTiVfyPvJZtrM by GoatJamesAz@owo.cafe
2023-08-10T19:48:45Z
0 likes, 0 repeats
@mjg59 Literally approaching Dune mentats with every passing second. We still need melange, but for computers
(DIR) Post #AYgTvJOscKF2YVQfIW by dalias@hachyderm.io
2023-08-10T14:59:12Z
1 likes, 0 repeats
@ljrk @mjg59 Sadly most of the teams doing performance oriented riscv designs are on the speculative bandwagon. 😫 🤦
(DIR) Post #AYgUYeDX9bNQPbsXjM by dalias@hachyderm.io
2023-08-10T15:01:57Z
0 likes, 0 repeats
@LunaDragofelis @mjg59 This would be great if compiler authors would stop bloating memory requirements. make -j128 would be awesome but nowadays that'd need 256GB of ram. 🤬
(DIR) Post #AYgUYioC5F4ueT3sQa by lanodan@queer.hacktivis.me
2023-08-13T09:54:00.311980Z
0 likes, 0 repeats
@dalias @LunaDragofelis @mjg59 I also think compilers being multicore-aware themselves would be quite welcome as AFAIK a lot of compiler time is dealing with headers (specially in C++), instead we get hacks like jumbo-builds which severely bloats the memory requirements.
(DIR) Post #AYgUYkw4AwZ1FSlBya by dalias@hachyderm.io
2023-08-10T15:05:10Z
0 likes, 0 repeats
@LunaDragofelis @mjg59 So parallelism helps to some point but really we also need ultra short pipelines where you get acceptable single core performance without speculation.
(DIR) Post #AYgUczMiT3Yb9zFAtE by dalias@hachyderm.io
2023-08-10T20:50:42Z
1 likes, 0 repeats
@lispi314 @LunaDragofelis @mjg59 Also: Do you have any idea how much power it takes to operating that much ram? Non-starter for a laptop or phone. Battery life would be abysmal.
(DIR) Post #AYgWFjUTWX1lAmuZ96 by lanodan@queer.hacktivis.me
2023-08-13T10:13:01.246724Z
0 likes, 0 repeats
@thesamesam @LunaDragofelis @dalias @mjg59 Well Firefox's buildsystem is probably also one of the most hacky ones around.
(DIR) Post #AYhM7JZ3ECTa42MJDU by alwayscurious@infosec.exchange
2023-08-13T19:53:08Z
0 likes, 0 repeats
@mjg59 thoughts on speculative taint tracking? Or just refusing to speculatively access anything that is not already in L1 cache and the L1 TLB?